1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method thereof. More specifically, the present invention relates to a multi chip package-type semiconductor device having a structure in which a plurality of semiconductor chips are stacked vertically, and to the manufacturing method thereof.
2. Description of the Related Art
Pursuant to the recent demands for higher functionality and lighter, thinner and smaller electronic equipment, high-density integration and even high-density mounting of electronic components have advanced, and the downsizing of semiconductor devices used in the foregoing electronic equipment is also advancing faster than ever before.
As a method of manufacturing a semiconductor device such as an LSI unit or an IC module, as shown in FIG. 10, there is a method of manufacturing a Stacked MCP (Multi Chip Package) which is obtained by foremost facing the circuit surfaces of a plurality of semiconductor elements 2 determined as being non-defective in electrical property testing, in the same direction and stacking such semiconductor elements 2 on a support substrate 43 in a manner where the electrode pads (not shown) of the respective semiconductor elements are exposed without being hidden by the other semiconductor elements, electrically connecting the electrode pads of the semiconductor elements and the support substrate 43 via a wire bonding 46, thereafter sealing the product with a sealing resin 55, forming solder balls 56 as external connecting terminals, and individually cutting the semiconductor elements to complete the semiconductor devices (for instance, refer to Japanese Patent Application Publication No. 2002-33442).
Nevertheless, with a conventional semiconductor device obtained as described above, since only one side or both sides of the semiconductor element can be electrically connected with the support substrate, since wire bonding is used for the connection, there is a limit in that only two semiconductor elements can be simultaneously operated.
Moreover, there are demands for thinning the package in which a plurality of semiconductor elements are stacked, and in order to meet such demands, it is necessary to reduce the thickness of each semiconductor element and mount such thin semiconductor elements, and reduce the height of the connecting members such as a wire bonding.
Nevertheless, the connection of the wire bonding to be connected to the semiconductor element needs to pass above the mounted semiconductor element, but if the height of the connecting member is low, it will connect with the semiconductor element and cause a short-circuit.
Thus, in order to prevent the portions other than the electrodes of the semiconductor element from contacting the wire bonding, as shown in FIG. 11, an insulating material layer 34 as a protective resin layer is formed on a part of the electrode-forming part or the side face or back face of the semiconductor element 2 in order to prevent short-circuits (for instance, refer to Japanese Patent Application Publication No. 2009-49118).
When simultaneously operating more than two semiconductor elements, it is necessary to stack the semiconductor elements so as to be directly connected with the two semiconductor elements to be operated for simultaneous operation with the two semiconductor elements. Thus, the size of the semiconductor device becomes large, and the junction temperatures in the semiconductor elements will increase due to the poor heat radiation of the stacked structure, thereby causing a problem in that the foregoing simultaneous operation is not possible.
As recent trends, the downsizing of the semiconductor package size and the increase in the number of semiconductor elements that can be mounted are being demanded. In order to meet these demands, the following have been proposed and developed; namely, a semiconductor device having a POP (Package on Package) structure in which another semiconductor package or a circuit board is stacked on a semiconductor package (Japanese Patent Application Publication No. 2008-218505) and a semiconductor device having a TSV (Through Silicon Via) structure (Japanese Patent Application Publication No. 2010-278334).
A conventional POP structure semiconductor device is now explained based on FIG. 8. POP (Package on Package) is a package mode in which a plurality of different LSIs are assembled as individual packages, tested, and then stacking the packages thereafter.
The semiconductor device 40 is configured by another semiconductor package 42 being stacked on a semiconductor package 41. A semiconductor element 44 is mounted on the substrate 43 of the lower semiconductor package 41, and electrode pads (not shown) formed at the periphery of the semiconductor element 44 and electrode pads 45 on the substrate are electrically connected via wires 46. The entire surface of the semiconductor element 44 is sealed with a sealing member 47. In addition, the semiconductor package 41 and the semiconductor package 42 are mutually electrically connected based on reflow via external connecting terminals 48 (solder balls) formed on the lower face of the semiconductor package 42.
POP is advantageous in that the mounting area can be increased upon mounting devices as a result of stacking a plurality of packages as described above, and, since each package can be individually tested, the production yield loss can be reduced. Nevertheless, with POP, since the individual packages are individually assembled and the completed packages are stacked, it is difficult to reduce the assembly costs based on the reduction (shrinkage) of the semiconductor element size, and there is a problem in that the assembly cost of the stacked module is extremely expensive.
A conventional TSV structure semiconductor device is now explained with reference to FIG. 9. As shown in FIG. 9, a semiconductor device 50 has a structure in which a plurality of semiconductor elements 51 mutually have the same function and structure and which are respectively prepared using the same manufacture mask and one interposer substrate 52 are stacked via a resin layer 53. Each semiconductor element 51 is a semiconductor element using a silicon substrate, and is electrically connected to the upper and lower adjacent semiconductor elements via multiple through electrodes (TSV: Through Silicon Via) 54 that penetrate the silicon substrate and sealed with sealing resin 55. Meanwhile, the interposer substrate 52 is a circuit board made of resin, and a plurality of external connecting terminals (solder balls) 56 are formed on the back face thereof.
With a conventional TSV (Through Silicon Via) stacked module structure, since through-holes are provided to each of the individual semiconductor elements, there is a possibility that the semiconductor element will become damaged, and it is also necessary to add several complex and costly wafer processes of forming via electrodes in the through-holes. Thus, this resulted in a considerable cost increase of the overall vertically stacked module. Moreover, with the conventional structure, it is difficult to stack and mount chips of different sizes and, due to the “addition of different rewiring layers for each layer”, which is essential upon the lamination of the same chips as in a memory device, the manufacture costs increase considerably in comparison to ordinary memory device modules, and there is a problem in that the cost reduction based on mass production cannot be expected.